Ron's Radio Corner

Friday, 9 February 2018

Discone antennes cover a wide frequency range. MFJ has introduced a new discone antenna: the MFJ-1868.

It is designed to receive radio signals from 25 - 1300 MHz and to transmit from 50 - 1300 MHz (up till 200 Watts RF power). Interesting because it covers 6m, 4m, 2m, 70cm and the 23 cm band.A discone antenna is omnidirectional, vertically polarized and has a rather narrow radiation pattern in the horizontal plane. This makes the antenna sensitive in the direction of the horizon. SWR remains below 1:2 for the 50...1300 MHz frequency range.Interesting if you do not want your garden covered with lots of antennes.The MFJ-1868 has a vertical whip affixed to the centre in order to extend the low frequency response.Price of this antenna: appr. $70

Sunday, 24 December 2017

Some collections are special and deserve to be maintained. The collection of Mr. Teyler from Haarlem is such a special collection. This week we visited the Teylers museum and were able to see interesting items such as Leyden jars, 19th century light bulbs, ancient skeletons and the study room of prof. Lorentz.More info: https://www.teylersmuseum.nl/nl

Saturday, 9 September 2017

Today I kept track of the signal strength of the satellite TV signal from the satellite Astra 23.5 (Astra 3B transmits just above 11 GHz).It was interesting to see that a dip in the signal strength came with the bad weather that arrived from the North Sea;

Monday, 4 September 2017

I downloaded KiCad version 4.0.7 which is an open source Electronics Design program. With the schematic editor you can create your design
without limit; there are no paywalls to unlock features. An official library
for schematic symbols and a built-in schematic symbol editor are available.More
info here: http://kicad-pcb.org/The first schematic with this program:

Friday, 25 August 2017

This radio uses two receiver chains; the supply voltage needed for the transistor amplifier is generated by a strong local broadcast station to which diode receiver number 1 (left side of the schematic) is fix-tuned. Tune with the aid of a meter and adjust for maximum detection. Low-level stations are detected with the diode receiver number two (right side of schematic). Use a germanium low signal AF type transistor (AC151, 2SB187) and Ge-diodes (AA119, AA112, AO85...). Design coil1 and 2 in such a way that Medium Wave broadcast stations are received.

A supply voltage as low as 450 mV produces audible signal amplification. Of course you have to use TWO antennas.The designer of this radio uses for receiver number 2 (right) a loop (frame) antenna, for receiver number 1 (left) a a 20 meters outside antenna (wire). Receiver 1 generates a supply voltage of approx. 900 mV under load of receiver number 2.Adjust the variable 250 kOhms resistor to approx 50 % of the voltage generated by receiver number 1 voltage (measured at + pole). Best value for 10 kOhms trim pot is 3 to 6 kOhms.

Monday, 21 August 2017

Hans Summers, G0UPL, has developped a new transceiver:It is a mono-band 5W CW transceiver, with tons of features, including WSPR beacon, built-in alignment/test equipment, iambic keyer, CW decoder, rotary-encoder tuned synthesised VFO, and more. Price is appr. 42€. The kit is available for 80, 60, 40, 30, 20 or 17m bands and can be ordered here:https://shop.qrp-labs.com/qcx .The 137-page assembly/operation manual can be downloaded here http://qrp-labs.com/qcx and includes circuit diagram and comprehensive description of circuit operation.